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Brief Introduction
I. Applications Ion exchangers are primarily used for producing purified and ultrapure water, with extensive applications across pharmaceutical, chemical, electronic, coating, beverage, and medium/high-pressure boiler feedwater industries. They serve as pretreatment systems for water purification in boilers, power plants, chemical processing, textiles, biomedicine, electronics, and nuclear applications. Additional uses include: hard water softening, deionized water production, food/pharmaceutical decolorization/purification, precious metal/chemical recovery, and electroplating wastewater treatment. II. Classification 1. Sodium Ion Exchangers Primarily for pretreatment in boilers, power plants, and various industries (chemical, textile, pharmaceutical, etc.) requiring purified water. 2. Dual Beds Cation-anion exchange systems connected in series for water desalination. 3. Mixed Beds Contain blended cation/anion resins in specific ratios. The immediate recombination of H⁺ and OH⁻ ions produces highly purified water, typically used after primary dual beds or standalone for lower purity requirements. III. Operating Principles & Exhaustion Control 1.Working Principle Ion exchange reactions: Cation resin: (H-R) + M⁺ → (M-R) + H⁺ Anion resin: (OH-R) + X⁻ → (X-R) + OH⁻ (M⁺ = metal ions; X⁻ = anions. Regeneration reverses these reactions.) 2. Exhaustion Control Unit System: Each desalination train includes one cation bed, (decarbonator), and anion bed. All beds regenerate simultaneously upon either bed's exhaustion. Header System: Parallel beds regenerate individually when exhausted, improving resin utilization and reducing chemical consumption. (1) Monitoring Principles Cation beds: Exhaustion detected by Na⁺ breakthrough (weakest adsorbed ion: Fe3⁺ > Al3⁺ > Ca2⁺ > Mg2⁺ > Na⁺ > H⁺). Reaction: Aⁿ⁺ + nRH → RₙA + nH⁺ Anion beds: Exhaustion detected by HSiO₃⁻ breakthrough (weakest adsorbed ion: SO₄2⁻ > NO₃⁻ > Cl⁻ > OH⁻ > HCO₃⁻ > HSiO₃⁻). Reaction: Bᵐ⁻ + mROH → RₘB + mOH⁻ (2) Control Methodology Header systems (e.g., Chengdu Biological Products Institute's 5 t/h system: sand filter → activated carbon → cartridge filter → cation → 1st anion → 2nd anion → mixed bed → polishing filter → storage tank) optimize resin usage through unit exhaustion control. 3. Output Water Quality After primary dual-bed treatment: Conductivity (25°C): <10 μS/cm Silica content: <100 μg/L |
